A hard-disk drive (HDD) is a non-volatile storage device that is housed in a protective enclosure and stores digitally encoded data on one or more circular disks having magnetic surfaces. When an HDD is in operation, each magnetic-recording disk is rapidly rotated by a spindle system. Data is read from and written to a magnetic-recording disk using a read-write head that is positioned over a specific location of a disk by an actuator. A read-write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk. A write head makes use of the electricity flowing through a coil, which produces a magnetic field. Electrical pulses are sent to the write head, with different patterns of positive and negative currents. The current in the coil of the write head induces a magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.
HDDs are being manufactured which are hermetically sealed with helium inside.
Further, other gases that are lighter than air have been contemplated for use as a replacement for air in sealed HDDs. There are various benefits to sealing and operating an HDD in helium ambient, for example, because the density of helium is one-seventh that of air. Hence, operating an HDD in helium reduces the drag force acting on the spinning disk stack and the mechanical power used by the disk spindle motor. Further, operating in helium reduces the flutter of the disks and the suspension, allowing for disks to be placed closer together and increasing the areal density (a measure of the quantity of information bits that can be stored on a given area of disk surface) by enabling a smaller, narrower data track pitch. The lower shear forces and more efficient thermal conduction of helium also mean the HDD will run cooler and will emit less acoustic noise. The reliability of the HDD is also increased due to low humidity, less sensitivity to altitude and external pressure variations, and the relative absence of corrosive gases or contaminants.
Electronic systems that require a hermetically-sealed internal volume (e.g., a lighter-than-air gas-filled, sealed HDD) need a way of preventing the occurrence of leakage through the interface between the cover and the corresponding enclosure base to which the cover is coupled. One approach is to utilize two covers: (1) one (a “first cover”) being the typical HDD cover coupled to the base with fasteners and with a gasket seal therebetween, but not hermetically-sealed, with (2) another cover (a “second cover”) being welded to the base over the first cover, such as by laser welding. However, sealing approaches involving laser welding secondary covers to the base are a relatively costly process in the context of the mass production of HDDs, with strict surface finish requirements and the cost of the welding equipment being main contributors to the cost. Furthermore, the welded seam is often a weak point, which may be damaged in the field by rough handling of the devices, whereby consequent leaks may result in an increased drive failure rate as compared to non-sealed products. Based at least on the foregoing, challenges remain with welded covers for hermetically-sealed HDDs.
Any approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.